The present invention relates to apparatus for determining an axis of a spherical ball which axis includes its geometric center and its center of gravity.
The fact that the weight center is not located exactly at the geometric center of a spherical ball is a widely known phenomenon.
Various studies of this unbalanced condition have been made. In the case of a golf ball, this phenomenon is described in detail by Olson et al in U.S. Pat. No. 4,111,038. Their findings showed this unbalanced condition to cause a golf ball to possibly veer undesirably when being putted. Further recited in their invention is a method and apparatus for locating an axis in an unbalanced golf ball containing both its geometric center as well as its center of gravity and a method for indelibly marking the uppermost point of this axis. This finding allowed for a certain control over this undesirable veering when a golf ball is being putted.
Their method for locating this axis involved freely floating a golf ball in water whose density had been enhanced by using magnesium sulfate and whose surface tension had been modified using propylene glycol.
Some of the FREONS currently being produced have densities greater than that of an ordinary golf ball. As an example, FREON 113 has a density of approximately 0.910 ounces per cubic inch at room temperature, while FREON 11 has a density of approximately 0.860 ounces per cubic inch at room temperature. This compares with an ordinary golf ball that has a density of approximately 0.650 ounces per cubic inch. Hence, it can be seen that an ordinary golf ball will float in both FREON 113 and FREON 11. Additionally, FREONS have the further advantage of having less surface tension and do not ordinarily require surface tension modifiers such as is used in the Olson, et al method described above.
Present invention does not utilize densifying agents and a water mix to cause a ball to float, but rather employs liquids of sufficient density such that a chosen ball will ordinarily float when placed in such liquids. Further, the chosen ball is contained in a closely fitted and especially designed cup when being floated such that fluid friction causes the ball to come to rest in a much shorter period of time than it would if freely floated. More specifically, a container of adequate size is filled to a predetermined level with a liquid such as FREON 113 or FREON 11 such that when the closely fitted and especially designed cup containing a ball such as a golf ball is lowered into the container filled as above with one of the chosen liquids to a depth such that the ball floats, the heavy portions of the ball will rotate by gravity to the lower-most position over time and the desired axis containing the balls' geometric center and its center of gravity will become vertical and hence, determined. Further, the clearance between the inner spherical diameter of the especially designed cup and the outer spherical diameter of the ball being tested is of primary importance. The inner spherical diameter of the especially designed cup should be just large enough such that the outer spherical diameter of the ball to be tested fits with sufficient clearance so the ball will rotate freely by gravity when floated, but close enough such that maximum fluid friction in the liquid trapped in the narrow gap remaining between the inner spherical diameter of the especially designed cup and the outer spherical diameter of the ball, is attained. In this manner, the heavy portion of the ball being tested will rotate by gravity to the bottom-most position in the desired least amount of time.
Additionally, this "contained floating" apparatus allows for raising the cup and the ball being tested from the chosen liquid without distrubing said balls' relative position while providing for a more convenient method of marking the upper-most point of said axis.